Not sure how to set compression on but the drive recognizes DDS1, DDS2, and
DDS3 tapes. The only problem you will have using the 120 tapes is the amount
of data store per tape will not match the advertised size. Some items to
look at for backup speed. Cleanliness of tape head (cut down on re-writes),
buffer space available for pooling data to be written (usually not a
problem, most slow disc drives are still faster than fast tape drives), what
IO channel is the tape on (separate SCSI cards are helpful), and finally
(not necessarily the last) CPU utilization (is the system busy doing
something else).
Look at the tape drive during backup, is it constantly going, or are there
times when it stops? If the tape is going constantly then your system is
probably keeping up with the data flow and it is just going to take 50
minutes. Another option, if using DDS2 tapes, put your DDS2 drive back
on-line and do a parallel backup. (Unless of course your system is unable to
feed one drive sufficiently, don't look for miracles, that it will suddenly
feed two.

James

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On
Behalf Of Connie Sellitto
Sent: Monday, November 15, 1999 10:05 AM
To: [log in to unmask]
Subject: DDS3 - compression


Hello Listers,

I sent out the following directly to Neil - no response to date - can any
of you help? Thank you!

 ---------------------------------------------------------------------------
--------------------------------------
>>Hello Neil,
Hoping you can help... I searched HP3000 List archives for 'DDS3', and
found your postings regarding your experiences with a DDS3 drive.  I'm
running a 937RX with 9.6 Gb disk, about 4.5 used, under MPE/iX 5.5.  We
just purchased a used DDS3 to replace our DDS2 because we were told it
would reduce backup time.  According to the HP reseller, no config changes
were needed, just power down the system, install the DDS3 drive, bring the
system up, and the system would recognize the new drive.

Well, the backup did work, but it didn't take any less time (about 50
minutes).

I noticed you used a 125 m tape - I have only 120 m DDS2,  Will they work?

Also, how do I configure the drive for compression?  SYSGEN ld on ldev 8
has:
ID: HPC1533A
MPETYPE: 4 MEPSUBTYPE: 7
CLASS:  TAPE       DAT

What do I have to do to use this drive as intended?

tia for your help,
Connie Sellitto